The conventional linear roller guide device of this type generally has a structure in which a movable block is movably supported on a track rail through a number of rollers. The guide device using rollers has an advantage of high rigidity and high load bearing ability in comparison with the guide device using balls. The movable block comprises a block body and side covers to be attached to both end portions of the block body. The block body is provided with a roller rolling surface and a roller returning passage for endlessly circulating a roller row, and the side cover is provided with a direction changing passage for connecting the roller rolling surface side to the roller returning passage.
Both sides of the roller rolling surface of the movable member are provided with a roller end surface guide wall for guiding an end surface of the roller, and each of the roller returning passage and the direction changing passage is also provided with a guide wall which is formed to be continuous to the roller end surface guide wall. whereby the end surfaces of the roller are guided in entire circulating passage so as to orderly circulate the rollers.
Conventionally, as to structural members such as the roller returning passage, the side cover and the roller end surface guide wall or the like, an attempt to reduce a manufacturing cost has been made by employing resin moldings as the structural members.
However, the above conventional linear roller guide devices entail drawbacks as described hereunder:
1+L The manufacturing process is complicated.
That is, each of the resin molded members is a molded member which is formed separately from the block body, so that a process of assembling the respective resin molded members is required after separately forming the respective members.
2+L The circulating defects of the roller at the roller rolling surface are liable to occur.
Namely, when assembled the resin molded members, irregularities are liable to occur at a connecting portion between the roller returning passage and the direction changing passage, and at a connecting portion between the roller rolling surface and the direction changing passage, so that there may be posed a problem, for example, that a smooth circulation of the rollers is obstructed and a problem of generation of an abnormal noise.
3+L The circulating defects of the roller at the roller end surface are liable to occur.
In particular, in case of the roller, it is required to prevent skew of the roller (i.e. blurring of a rotational axis of the roller). In order to prevent the skew, it is required to guide the end surface of the roller not only in a range of a loaded area of the roller rolling surface but also in all around of an endlessly circulating passage ranging from the direction changing passage to the non-loaded area of the roller returning passage.
FIG. 15(a) shows a state that the roller 100 changes a rolling direction thereof form an unloaded area .alpha. to a loaded area .beta. of the direction changing passage. At the time of direction changing of the roller 100, for example, as schematically shown in FIGS. 15(b) and 15(c), when the roller 100 moves from the loaded area .alpha., and then enters into the loaded area .beta. in a skewed state, one end portion of the roller 100a of the roller 100 will firstly collide against the roller rolling surface 101 in the loaded area, so that the smooth movement of the roller 100 is obstructed. In addition, an edge load may occur at the end portion 100a of the roller 100 entering into the loaded area .beta., so that the roller 100 per se and the roller rolling surface 101 are damaged thereby to deteriorate durability of the guide device. Further, vibration of the roller and changes in rolling resistance during the circulation of the rollers will occur thereby to obstruct the smooth circulation of the rollers.
In order to prevent such problems, hitherto, the end surface of the roller is formed so as to be guided by the roller end surface guide wall provided at both sides of the roller rolling surface and passage walls provided at the direction changing passage and the roller returning passage. However, since the guide system is formed by connecting the discontinuous roller end surface guide wall, direction changing passage and roller returning passage, a sticking of the roller is liable to occur due to non-uniformity in a width of the respective passages and the irregularities of the connected portions thereby to also obstruct the smooth circulation of the rollers.
4+L A falling-out of the roller is required to be prevented.
On the other hand, hitherto, in order to prevent the roller from falling out from the movable block when the movable block is detached from the track rail, there is a well known structure in which a chamfered portion is provided at end portion of the roller and an engaging projection with which the chamfered portion is engaged is provided at the roller end surface guide wall formed along the roller rolling surface.
However, in case of such roller retaining system, when the engaging projection interferes with the roller during the circulation of the roller, the smooth circulation of the roller is obstructed. Therefore, when assembling the guide device, it is required to provide a small gap or clearance between the roller and the engaging projection so as not to interfere the engaging projection with the roller. However, it was difficult to provide the engaging projection to an accurate position.
In addition, the chamfered portion is required to be provided, so that an effective length for bearing the load is disadvantageously shortened in a length corresponding to the length of the chamfered portion, thereby to lower the load bearing ability.
On the other hand, there is also another well-known roller retaining system in which a number of rollers are retained in form of a chain by linking the rollers in a roller chain. However, in the case of such rollers retained in the roller chain, a problem of a running-out of the roller chain will arise during the circulation of the rollers. Therefore, it is necessary to guide the roller chain along the predetermined track. However, it was difficult to accurately guide the roller chain.
The first invention has been achieved for solving the problems described above, and an object of this invention is to provide a linear roller guide device enabling to reduce the assembling processes, to accurately position the structural members to a predetermined positions of the block body, and to secure the smooth circulation of the rollers by integrally forming at least one of the roller returning passage, roller end surface guide wall and direction changing passage with the block body.
An object of the second invention is, in addition to the object described above, to provide a linear roller guide device enabling to securely prevent the roller chain from running-out during the circulation of the rollers linked by the roller chain.